Dave,
It isn't an urban myth, but a fact, you only have to read the literature supplied with the product.
Loctite has thousands of different formulae that never reach market, it is devoloped for a customers personal sticky problems. When I worked in computer peripherals manufacture, the Loctite guy almost had a permanent home in the factory, they were making up special blends for us all the time, even ones that would work in the slightly reduced pressure of a cleanroom.
I too use normal Loctite in an interferrance or press fit, but I make sure at least one of the surfaces is slightly rough, to make sure that at least a little of the adhesive is carried into the joint.
If I want a real non come apart joint, but on metals that would be liable to distort if too much pressure is applied, I actually make the parts a tight sliding fit, then put a very fine straight knurl on the male part (not mine), then put the adhesive on before assembly. At a real push they can be got apart, but only after the Loctite is destroyed by heat, otherwise it is a joint for life.
John